CHAPTER XVII 

 IDEALISM AND COMMON SENSE 1 



Mental adaptation Objections to the hypothesis that minds are products 

 of evolution Memory Sense-impressions What a sheet of paper means 

 We are directly aware of nothing but a stream of feelings The mental differences 

 between the higher and the lower animals How we construct external objects 

 The differences between feelings ordinarily recognized as such, and those which 

 are thought of as properties of external objects Idealism and common sense 

 Coherent thought and common sense Except at rare intervals all men think in 

 terms of common sense There are no thorough-going idealists The two views 

 are quite incompatible Invariable succession and necessary succession. 



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$47. f | ^HE bodies of the higher animals are compounded of 

 ' characters/ which, in turn, are compounded of 

 smaller characters. With the possible exception of 

 a few traits (by-products of evolution) correlated to more useful 

 traits, the larger and older characters hands, limbs, hair, nails, 

 and the like are almost all adaptations ; or, if vestigial remains, 

 have been adaptations. The smaller and newer characters, the 



1 Many of the words used in the following discussion (chapters xvii., xviii. 

 and xix.) have gathered special meanings during the course of controversy. 

 By matter I mean something which is not mind, but which exists external to mind, 

 and has properties that excite sensations in it, and is thus mediately known to it. 

 By feeling I mean not merely sensation, but any state of consciousness. By 

 mind I mean the stream of feelings. By idealism I mean the philosophy which 

 supposes that " the sensations, which, in common parlance, we are said to receive 

 from objects, are not only all we can possibly know of the objects, but are all that 

 we have any ground for believing to exist," and which declares " we have no 

 evidence of anything which, not being itself a sensation, is a substratum or 

 hidden cause of sensations," and that " such a substratum is a purely mental 

 creation to which we have no reason to think that there is any corresponding 

 reality exterior to our minds " (J. S. Mill, Examination of Sir William Hamilton's 

 Philosophy, 3rd ed.). By common sense I mean merely the notion, held con- 

 sciously or unconsciously by every one during ordinary thought, that our minds 

 tell us of a universe of real or material things external to the minds. I do not use 

 the word as implying immediate or intuitive cognition of real things. I have 

 thought the discussion necessary, partly because I wish, as far as possible, to 

 establish the nature of the relation between mind and body, and partty (since it is 

 sometimes said that science explains nothing, and that there is no such thing as 

 necessary truth) because I wish to define what appears to me to be the scope of 

 science, and the significance of certain terms that I use, such as cause, invariable 

 succession, necessary succession, necessary truth, explain, and understand. 

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